The duty of a man is to be useful to his fellow-men; if possible, to be useful to many of them; failing this, to be useful to a few; failing this, to be useful to his neighbours, and, failing them, to himself: for when he helps others, he advances the general interests of mankind. Just as he who makes himself a worse man does harm not only to himself but to all those to whom he might have done good if he had made himself a better one, so he who deserves well of himself does good to others by the very fact that he is preparing what will be of service to them.”

It also tells us that the key to a serene life is the realisation that some things are under our control and others are not: under our control are our values, our judgments, and the actions we choose to perform. Everything else lies outside of our control, and we should focus our attention and efforts only on the first category.

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For Seneca and the Stoics, the only life worth living is one of moral rectitude, the sort of existence we look back to at the end and can honestly say we are not ashamed of.

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Seneca wrote a much longer essay on the same topic of what makes for a happy life, one that includes a set of seven ‘commandments to himself’ (from book XX ‘Of a Happy Life’). They provide a way to philosophically structure our own lives:

I) I will look upon death or upon a comedy with the same expression of countenance.
II) I will despise riches when I have them as much as when I have them not.
III) I will view all lands as though they belong to me, and my own as though they belonged to all mankind.
IV) Whatever I may possess, I will neither hoard it greedily nor squander it recklessly.
V) I will do nothing because of public opinion, but everything because of conscience.
VI) I will be agreeable with my friends, gentle and mild to my foes: I will grant pardon before I am asked for it, and will meet the wishes of honourable men half-way.
VII) Whenever either Nature demands my breath again, or reason bids me dismiss it, I will quit this life, calling all to witness that I have loved a good conscience, and good pursuits.”

— From A Guide to the Good Life – The Ancient Art of Stoic Joy by WILLIAM B. IRVINE

We should remind ourselves that “this mortal life endures but a moment,” meaning that we soon will be dead.” Putting annoying incidents into their cosmic context, he thinks, will make their triviality apparent and will therefore alleviate our annoyance.

One of their sting-elimination strategies is to pause, when insulted, to consider whether what the insulter said is true. If it is, there is little reason to be upset.

Another sting-elimination strategy, suggested by Epictetus, is to pause to consider how well-informed the insulter is. He might be saying something bad about us not because he wants to hurt our feelings but because he sincerely believes what he is saying, or, at any rate, he might simply be reporting how things seem to him. Rather than getting angry at this person for his honesty, we should calmly set him straight.

One particularly powerful sting-elimination strategy is to consider the source of an insult. If I respect the source, if I value his opinions, then his critical remarks shouldn’t upset me.

Suppose, however, that I don’t respect the source of an insult; indeed, suppose that I take him to be a thoroughly contemptible individual. Under such circumstances, rather than feeling hurt by his insults, I should feel relieved: If he disapproves of what I am doing, then what I am doing is doubtless the right thing to do. What should worry me is if this contemptible person approved of what I am doing. If I say anything at all in response to his insults, the most appropriate comment would be, “I’m relieved that you feel that way about me.”

When we consider the sources of insults, says Seneca, we will often find that those who insult us can best be described as overgrown children.’ In the same way that a mother would be foolish to let the “insults” of her toddler upset her, we would be foolish to let the insults of these childish adults upset us.

In other cases, we will find that those insulting us have deeply flawed characters. Such people, says Marcus, rather than deserving our anger, deserve our pity’

keep in mind, when insulted, that we ourselves are the source of any sting that accompanies the insult. “Remember,” says Epictetus, “that what is insulting is not the person who abuses you or hits you, but the judgment about them that they are insulting.” As a result, he says, “another person will not do you harm unless you wish it; you will be harmed at just that time at which you take yourself to be harmed.”‘ From this it follows that if we can convince ourselves that a person has done us no harm by insulting us, his insult will carry no sting.

as Epictetus puts it, “what upsets people is not things themselves but their judgments about these things.”

in his consolation to Polybius, who was grieving the death of his brother, Seneca writes, “Nature requires from us some sorrow, while more than this is the result of vanity. But never will I demand of you that you should not grieve at all.”

“let your tears flow, but let them also cease, let deepest sighs be drawn from your breast, but let them also find an end.”

Anger, says Seneca, is “brief insanity,” and the damage done by anger is enormous: “No plague has cost the human race more.”

anger can destroy us individually.

Being angry, Seneca concludes, is a waste of precious time.

Reason,” he cautions, “will never enlist the aid of reckless unbridled impulses over which it has no authority.”

We should, he says, fight our tendency to believe the worst about others and our tendency to jump to conclusions about their motivations.

By allowing ourselves to get angry over little things, we take what might have been a barely noticeable disruption of our day and transform it into a tranquility-shattering state of agitation.

This is the problem with anger: It feels good to vent it and feels bad to suppress it.

many of the things we think are important in fact aren’t, at least not in the grand scheme of things.

“We are bad men living among bad men, and only one thing can calm us-we must agree to go easy on one another.”

It is not that we have a short space of time, but that we waste much of it. Life is long enough, and it has been given in sufficiently generous measure to allow the accomplishment of the very greatest things if the whole of it is well invested. But when it is squandered in luxury and carelessness, when it is devoted to no good end, forced at last by the ultimate necessity we perceive that it has passed away before we were aware that it was passing. So it is—the life we receive is not short, but we make it so, nor do we have any lack of it, but are wasteful of it.”